perf(server-renderer):normalizeValue function prioritizes the judgmen…

Created by: LockingReal

…t of values equal to 0, thereby improving performance

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• [√] Other, please describe:

Does this PR introduce a breaking change? (check one) When the value is equal to 0, it avoids two typeof judgments and one js object attribute value, which improves performance

• Yes
• [√] No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• It's submitted to the main branch for v2.x (or to a previous version branch)
• When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• All tests are passing: https://github.com/vuejs/vue/blob/dev/.github/CONTRIBUTING.md#development-setup
• New/updated tests are included

If adding a new feature, the PR's description includes:

• A convincing reason for adding this feature (to avoid wasting your time, it's best to open a suggestion issue first and wait for approval before working on it)

Other information: